1. Field of the Invention
The present invention relates to an orthogonal frequency division multiplexing (OFDM)-based receiving scheme, and more particularly to an integer frequency offset estimation scheme in an OFDM-based system.
2. Description of the Related Art
An OFDM scheme may be applied to various systems such as mobile communication, digital broadcasting, etc. Hereinafter a digital video broadcasting system will be described as an example of such various systems.
Digital video broadcasting is a digital television broadcasting specification in Europe. Digital video broadcasting includes digital video broadcasting-satellite (DVB-S), digital video broadcasting-terrestrial (DVB-T), and digital video broadcasting-handheld (DVB-H).
To demodulate the transmitted data, a receiver should recognize accurate frequency offset information. A prior art related thereto includes a scheme based on a continual pilot symbol correlation and a scheme based on a continual/scattered pilot symbol correlation.
The scheme based on a continual pilot symbol correlation receives two consecutive OFDM symbols and estimates an integer frequency offset using a correlation of continual pilots inserted to the same index of the two symbols. Such a scheme uses only the correlation provided by continual pilot symbols located on the same index.
The scheme based on a continual/scattered pilot symbol correlation uses two correlations between pilot symbols in two OFDM symbols. A correlation of continual pilots and scattered pilots located most adjacent to the continual pilots is used and simultaneously a correlation of continual pilots having the same index located within the two consecutive symbols is used, thereby estimating an integer frequency offset. Such a scheme employs only a part of information provided by the pilot symbols on the assumption that channel changes so fast.